Concentrations of trace elements, 10Be, and 26Al in marine opal from sediments of ODP Hole 177-1093

• Main Authors: Lal, D, Charles, Christopher D, Vacher, L, Goswami, J N, Jull, A J Timothy, McHargue, L, Finkel, R C
• Format: Other/Unknown Material
• Language: English
• Published: PANGAEA 2006
• Subjects: 177-1093; COMPCORE; Composite Core; Joides Resolution; Leg177; Ocean Drilling Program; ODP; South Atlantic Ocean; Antarc*; Antarctic; Antarctica
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.710927; https://doi.org/10.1594/PANGAEA.710927

Here, we provide evidence suggesting that marine (diatom) opal contains not only a high fidelity record of dissolved oceanic concentrations of cosmic ray-produced radionuclides, 10Be and 26Al, but also a record of temporal variations in a large number of trace elements such as Ti, Fe, Zn and Mn. This finding is derived from measurements in purified biogenic opal that can be separated from detrital materials using a newly developed technique based on surface charge characteristics. Initial results from a sediment core taken near the present-day position of the Antarctic Polar Front (ODP Site 1093) show dramatic changes in the intrinsic concentrations of, Be, Al, Ti, Fe, Mn and Zn in the opal assemblages during the past ~140 kyr BP. The results imply appreciable climatically controlled fluctuations in the level of bioreactive trace elements. The time series of total Be, Al, Ti, Fe and 10Be in the sediment core are all well correlated with each other and with dust records in the polar ice cores. The observations suggest that a significant flux of these trace metals to oceans is contributed by the aeolian dust, in this case, presumably from the Patagonia. This observation also allows determination of fluxes of dust-contributed 10Be to the Antarctica ice sheets. However, our data show that the relationships among the various metals are not perfectly linear. During periods of higher dissolved concentrations of trace elements (indicated by Fe and Ti) the relative concentrations of bioreactive elements, Be, Al, Mn and Zn are decreased. By contrast, the Fe/Zn and Fe/Mn ratios decrease significantly during each transition from cold to warm periods. The relative behavior could be consistent with any of the following processes: (i) enhanced biological productivity due to greater supply of the bioreactive elements (e.g. Zn) during cold periods (ii) increased biological and inorganic scavenging of particle active elements (e.g. Be and Al) during early interglacial periods (iii) differential uptake/removal of the metals by the ...